1. Technical Field
The present invention relates generally to sign and sign stand devices and more particularly to an improved resilient member for coupling an upright member to a base.
2. Discussion
Numerous sign stand devices have been designed for displaying advertisements and information to the public. These signs are typically positioned on an upright member that is either anchored in the ground, held in place by sand bags or other heavy objects, or spring-mounted on bases which allow the upright member to bend or deflect relative to the base, without tipping over, under high wind forces. Several spring-mounted sign stands are shown in U.S. Pat. Nos. 4,548,379; 4,569,499; 5,725,186 and co-pending patent application entitled "Improved Sign Stand For Flexible Traffic Control Signage", Ser. No. 09/133,107, filed Aug. 12, 1998, the disclosures of which are hereby incorporated by reference as if fully set forth herein.
Some prior art sign stands have a single spring as the resilient member for coupling the upright member to the base. Such prior art sign stands are susceptible to damage from prolonged exposure to high winds. This damage typically results from a torque moment created by the force of the wind acting against the sign which would twist the upright member relative to the resilient member. In prior designs where the resilient member is coupled to the upright member and/or base by one or more threaded fasteners, the action of the wind against the sign can produce a moment that will work against these fasteners, causing them to loosen. The loosening of these fasteners causes a corresponding reduction in the clamping force exerted by these fasteners, thus allowing relative movement at the interface between the upright member and/or base and the resilient member. The relative movement between the resilient member and upright member and/or base can damage the fastener as well as the abutting surfaces. In some extreme cases, the upright member carrying the sign could literally unscrew from the base.
In view of this problem, several designs were developed which utilized dual springs, or in the case of a single spring, welded connections wherein the resilient member would either be welded directly to the upright member and/or base or to a structural member, such as a length of square tubing, which would receive the upright member or couple to the base. While the welded connection provided improved resistance to the torque moment produced by the wind, the welded connection was susceptible to fatigue and fracture due to the cyclic nature of wind forces. Additionally, the welded connection prevented the servicing of worn or damaged components, requiring instead the wholesale replacement of significant assemblies rather than just the damaged components.
With respect to the sign stand design which utilizes two springs, this design allows the moment produced by the wind forces to be absorbed by the two springs which are laterally offset from the axis of the upright member. While this design has significantly reduced the occurrence of damage to sign stands resulting from prolonged exposure to high winds, several drawbacks have been noted. These drawbacks include increased weight, increased size, additional fabrication labor and additional cost which are a byproduct of the duplication involved by including the second spring assembly.
Consequently, there remains a need in the art for an improved resilient member which is easily fabricated, relatively low in weight, compact in size and easily serviced.